1. Field of the Invention
This invention relates to the cooling of moving metal strip or sheet, particularly to the soft cooling of such products with a descending water-air mixture.
2. Description of Prior Art
The cooling of moving hot metal strip is old in the art, and commonly is achieved by flooding the hot metal strip with streams of cooling water, for example as shown in U.S. Pat. Nos. 5,390,900; 4,047,985; 4,415,381; 4,440,584, and 4,497,180. Cooling also may be effected by means of air-water sprays. An example is shown in U.S. Pat. No. 4,226,108 in which air-water sprays are directed vertically downwardly onto an upper surface of a moving hot metal strip and upwardly onto a lower surface of the strip. U.S. Pat. No. 4,098,495 shows cooling of a moving metal strip by means of an aerosol flowing across the width of the strip perpendicularly to its path of travel. U.S. Pat. No. 4,407,487 shows cooling of a moving metal strip by means of air-water sprays directed vertically upwardly and downwardly onto the upper and lower surfaces of the metal strip.
This invention is an improvement of the invention disclosed in U.S. Pat. No. 5,390,900, which is assigned to the assignee of the present invention and which is incorporated herein by this reference. That patent discloses a metal strip cooling system in which a descending stream of liquid water, from a waterwall cooling header, is used to cool a hot metal strip moving perpendicularly past the water stream. Variable cooling across the width of the strip is achieved by interposing a deflector, in the form of a slidable plate, in the path of the flow of air directed toward the water stream thereby to interrupt a portion of the air stream whereby a portion of the descending water stream is undiverted and contacts the moving metal strip to cool it, while another portion of the water stream is diverted by the air stream into a water collector.